The present invention relates to a stringed instrument and to a stringed instrument nut for use in a stringed instrument such as an electric guitar.
Referring to FIG. 7, a typical electric guitar typically includes a body 61, a neck 62, and a plurality of strings 64. Tailpieces 63 and bridges 67 are arranged on the body 61 opposite to the neck 62. A stringed instrument nut (hereafter simply referred to as a “nut”) 68 is arranged on the neck 62. Pegs 66, which form a tuning device, are attached to a head 65, which is set on a distal portion of the neck 62. Each string 64 has a basal end fixed to the corresponding tailpiece 63 and a distal end wound around and fixed to the corresponding peg 66. The bridges 67 and the nut 68 support the strings 64 in a state spaced from the surfaces of the body 61 and the neck 62. In this state constant tension, is applied to each string 64. When plucked, each string 64 vibrates in a state supported at contact points with the corresponding bridge 67 and the nut 68. When each string 64 vibrates, vibration in a basic-mode and vibration in wavelengths differing from that of the basic-mode vibration are mixed in a complicated manner to create a tone unique to a stringed instrument.
The electric guitar may be played using techniques known as arming and bending. Arming is a technique for changing the tones of the strings 64 by operating a tremolo arm and simultaneously changing the tensions of all the strings 64. Bending is a technique for changing the tone of each string 64 by individually changing the tension of each string 64. When the electric guitar is played using these techniques, the tension of each string 64 changes greatly. As a result, the position of each string 64 with respect to the nut 68 changes greatly. After the electric guitar is played with these techniques, the strings 64 may fail to return to their original positions because of friction resistance between the strings 64 and the nut 68. As a result, the strings 64 may go out of tune and affect the playing of the electric guitar. Each string 64 is tuned by turning the corresponding peg 66 to tighten or loosen the string 64 and adjust the tension on the string. A strong force may be applied to the peg 66 particularly when the string 64 is under high tension. This may reversely rotate the screw of the peg 66 and change the position of the peg 66.
To solve the above problems, Japanese Laid-Open Patent Publication No. 2003-122367 and U.S. Pat. No. 4,171,661 describe electric guitars that include a fastener for fixing strings to a nut. Referring to FIGS. 8 and 9, in the structures described in these documents, a surface 71 of a nut 68 is smoothly curved. Further, support walls 72 are formed on opposite ends of the nut 68. Each support wall 72 has a plurality of support grooves 73 for supporting strings 64. The support grooves 73 of one support wall 72 face the support grooves 73 of the other support wall 72. An inner bottom surface 73a of each support groove 73 is substantially flush with the nut surface 71. Each string 64 is received by two opposing support grooves 73 so as to restrict movement of each string 64 in the lateral direction of the neck 62.
Each string 64 is fixed in a state contacting the surface 71 of the nut 68 by a fastener 90. The fastener 90 includes pressing members 74 and adjustment screws 75. The pressing members 74 are arranged on the nut surface 71. The adjustment screws 75 fasten the pressing members 74 to the nut surface 71. A through hole 77 extends through the central portion of each pressing member 74. The adjustment screws 75 are inserted through the through holes 77. The adjustment screws 75, which are inserted through the through holes 77 of the pressing members 74, are mated with screw holes 76, which are formed in the nut surface 71. When the adjustment screws 75 are tightened, the pressing members 74 press the strings 64 against the nut surface 71 to securely fix each string 64. The fastener 90 prevents the electric guitar from going out of tune even when the electric guitar is played many times using the arming technique or the bending technique. The fastener 90 further prevents the position of each string 64 from changing after tuning.
However, when the strings 64 are securely fixed to the nut 68, stress may concentrate on points at which the strings 64 come in contact with the two ends 78a of each pressing member 74. In such a case, the strings 64 would have a tendency to break at these contact points. Accordingly, the curvature of the ends 78a of each pressing member 74 is smaller than the curvature of the other parts of the pressing member 74. This forms a clearance 79 between an end 78a of the pressing member 74 and the string 64 so that the pressing member 74 is slightly spaced from the nut surface 71. This structure reduces concentration of stress on each string 64. However, interference between each string 64 and the nut 68 may generate abnormal noise.
The nut 68 functions to stably support each string 64. It is thus preferable that the distal end of the nut 68 be sharp like a blade edge. However, when the nut 68 supports a string 64 with a sharp edge, only one point of the string 64 is supported by the edge. As a result, stress concentrates on the supported point of the string 64. This may easily break the string 64 or form a bending depression in the string 64 at the support point. Therefore, it is preferable that the nut 68 be formed so that its nut surface 71 is smoothly curved. More specifically, it is preferable that the nut 68 be formed so that the nut surface 71 extends, for example, along an arc. The nut 68 having the smoothly curved nut surface 71 enables a string 64 to be supported at one point and prevents stress from concentrating on that support point. However, when the nut surface 71 is smoothly curved, each string 64 approaches the nut surface 71 at locations close to the point of contact with the nut surface 71 and are gradually spaced from the nut surface 71 at locations farther from the point of contact. Accordingly, when vibrating, each string 64 has a tendency of coming into contact with the nut surface 71 and thus generating abnormal noise.
The generation of abnormal noise due to the nut 68 will now be described with reference to FIGS. 10(A) to 10(C). In the prior art, the nut 68 is shaped as shown in FIG. 10(A). The nut 68 minimizes the clearance formed between each string 64 and the nut surface 71. In this case, the angle a between the string 64 and the inner bottom surface 73a of the support groove 73 is substantially zero. Further, the string 64 is in contact with the nut surface 71 at an end portion of the nut 68 (as indicated by the ▴ symbol in FIG. 10(A)) when the string 64 is still. In this state, the pressing member 74 presses the string 64 against the nut surface 71 at a fixed point 80, as shown in FIG. 10(A). However, when the string 64 vibrates, the string 64 repeatedly comes into contact with and separates from the inner bottom surface 73a of the support groove 73 as shown in FIG. 10(B). In such a case, the string 64 may generate abnormal noise.
To solve this problem, the angle α between the string 64 and the inner bottom surface 73a of the support groove 73 may be changed so that it is greater than a predetermined value as shown in FIG. 10(C). In this case, the string 64 is supported in a state inclined relative to the nut 68. This keeps the point of contact between the string 64 and the inner bottom surface 73a of the support groove 73 located at the end portion of the nut 68. Referring to FIG. 7, the angle α is affected by various factors including the height of the bridges 67, the angle at which the neck 62 is connected to the body 61, the deformation amount of the neck 62, the shape of the surface to which the nut 68 is attached, and the method for fixing the nut 68. These various factors must be taken into consideration when determining the predetermined value angle α so that the point of contact between each string 64 and the nut 68 is maintained at the edge portion of the nut 68 not only when the strings 64 are still but also when the strings 64 are vibrating.
However, each string 64 is formed by a piano wire or by winding a metal wire around a piano wire, which serves as a core, in a coiled manner. The strings 64 formed from such a material are highly rigid and not flexible. It is thus difficult to extend the strings 64 along the nut surface 71 and bend the strings 64 at predetermined positions just by increasing the angle α between the strings 64 and the inner bottom surfaces 73a of the support grooves 73. As a result, the strings 64 separate from the nut surface 71 and form a gap between each string 64 and the nut surface 71. This may generate abnormal noise due to contact between each string 64 and the nut surface 71. For this reason, the fastener 90 is strongly required to minimize the generation of abnormal noise in addition to fixing each string 64 to the nut 68.